Identify the species that is predicted to be aromatic according to Hückel's rule. (I) (II) (III)

Step-by-step solution

According to Hückel's rule, a compound is aromatic if it is cyclic, planar, completely conjugated, and contains (4n + 2) electrons. In structure (I), the boron atom is sp^2 hybridized and possesses an empty p-orbital, allowing continuous conjugation. The system contains 4 electrons, which follows the 4n rule ( n=1 ). Thus, it is antiaromatic. In structure (II) (pyrrole), the nitrogen atom is sp^2 hybridized and its lone pair of electrons resides in an unhybridized p-orbital that participates in the ring's conjugati